1. Field of the Invention
The present invention relates to AF-area display apparatuses and AF-area operation apparatuses, and particularly to an AF-area display apparatus for displaying an AF-area as a subject area for automatic focusing (AF), in an imaging area of a camera, and an AF-area operation apparatus for implementing operation related to an AF-area position and the like.
2. Description of the Related Art
In an imaging system, such as a television camera, that converts through an image pickup device (such as CCD) an image of a photographic subject into an electrical signal (image signal), in general, the contrast system has been employed, as a method for automatic focusing (referred to as AF, hereinafter). In contrast system, by detecting a contrast of a photographic-subject image from an image signal (video signal) for the photographic-subject image introduced by an image pickup device, and by controlling focus (a focus lens) of the image pickup lens in such a way that the contrast becomes maximal, focusing is automatically implemented so as to be in the best condition.
In the contrast-system AF, in many cases, instead of the entire imaging area of a camera, only a photographic subject within part of the entire imaging area is utilized. For instance, focusing is controlled in such a way that, by extracting an image signal within a predetermined area, as a subject of AF, from the entire image signal for a photographic-subject image that is effectively picked up by a image pickup device, the contrast of the image becomes maximal. Accordingly, the subject of AF is limited to a photographic subject within a partial area. In addition, in the present specification, a subject area of AF is referred to as “AF area”, and the frame (outline of the AF area) that indicates the AF area is referred to as “AF frame”.
Moreover, for example, as Japanese Patent Application Laid-Open No. 2002-365519, a contrast-system AF is proposed in which, in accordance with operation of an operator, the position of an AF area can be shifted, and the AF area is displayed through an AF frame in the screen for a viewfinder.